Research rock star: Efficiency star


To ensure that electricity is available when we want it, we currently require a complex array of generating technologies. We put on costly peaking power plants to meet peak demands, such as on hot summer afternoons. But demand always plummets at night, preventing more extensive use of larger and more efficient baseload generating plants.

In response to this challenge, the University of Colorado and Clean Urban Energy Inc. (CUE) of Chicago, through a collaborative research agreement initiated in September 2008, have developed and deployed solutions that focus on the electrical demand of commercial buildings. Such buildings
typically reduce demand only sporadically during times of stress on the electrical grid. This new approach, however, creates
elasticity in the electric demand; an elasticity that is both continuous and scalable.

The core software engine, created at CU Boulder by architectural engineering professor Gregor Henze, Ph.D., and doctoral student Charles Corbin, implements model predictive control (MPC) strategies as part of a software-as-a-service (SaaS) platform. This platform shapes the electric demand of a building’s heating, ventilating and air-conditioning system by harnessing the building’s thermal mass embodied in concrete, furniture and books. In this way, the MPC platform turns buildings into thermal batteries capable of storage on a multi-megawatt scale.

The MPC modeling approach uses information about both building structure and operations to provide site-specific performance predictions. The core software engine then applies multi-attribute optimization techniques to help determine the most economical operation of the building for each day. Factored into this prediction are predicted local weather, carbon emissions at the source, fan and chiller efficiencies, and real-time electric market prices.

Ultimately, the technology uses the thermal mass of these buildings as large-scale thermal energy storage for urban smart grids. This storage capacity introduces demand flexibility into electric grids while improving the reliability of the grid itself. The ability to shape the electric demand of buildings allows for significantly expanded penetration of intermittent renewable energy and cogeneration systems with greatly reduced carbon emissions.

Prof. Henze, his research group and CUE are now investigating how portfolios of commercial buildings could be assembled to provide benefits in collaboration that exceed the benefits of individual buildings. Much like grid resources acting in concert to achieve economy and reliability, buildings within portfolios contain complementary features and capabilities that they plan to coordinate for synergistic effect. The technology harnesses the inherent physical and operating flexibility of commercial buildings to create value for, and provide services to, the electric grid at low cost.
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